1. Field of the Invention
The present invention relates to high frequency packages that contain semiconductor devices, optical semiconductor devices, and circuitries that use and control high frequency signals for microwave, millimeter wave, and optical communications in satellite, mobile, and aviation/marine communications.
2. Description of the Related Art
FIG. 1 of Japanese Laid-Open Patent Publication 2002-329800 discloses a substrate 4 loaded with a semiconductor device 2 thereon and a frame 7 that defines in its sides attaching areas 6, consisting of notches, for attaching input/output terminals 5. In addition, with FIG. 2 of the above-mentioned publication, a provision is made for transmission that covers an upper high-frequency bandwidth, by arranging a ceramic standing wall 10 in the notch and providing a groove 20 in the under-side of the standing wall 10, and by filling up the groove with a resin layer 11 having a dielectric constant less than that of ceramics so that the electrostatic capacitance between a line conductor 8 and the ground plane on the upper side of the standing wall 10 is diminished. Moreover, a range into which the resonance point of a high-frequency signal is upwardly shifted is discussed in terms of the relationship between the width of the groove 20 and the line conductor 8.
FIG. 1, both in Japanese Laid-Open Patent Publication 1993-110310 and in 1993-121888, disclose methods to shift upward or downward the resonance frequency of a cavity resonator by changing the size of the space between the package and the lid so as to avert generating a resonance that intrudes into the operating-frequency bandwidth of a microwave circuitry.
With the conventional semiconductor packages, an upward shift of a cut-off frequency determined by the capacitance between the ground conducting plane on the upper side of the standing wall and the line conductor has been discussed; however, effects on high frequency transmission lines (RF lines) caused by the notches themselves in the frame that contains the standing walls have not been set forth. In other words, as regards leakage and influx of unnecessary electric waves from RF lines typified by feedthroughs and from feedthrough lines for biasing, the notches (apertures) in the frame behave as slot antennas having specific resonance frequencies, and the resonance frequencies of the notches often reside in quantity within the frequency bandwidth in a high frequency band.